The present invention is directed to a drill stand with a base plate, a guide column connected to the base plate and a drilling device movably supported on the guide column. The guide column and the drilling device have mutually engageable guiding means. A feeding mechanism for the drilling device is supported on the guide column.
In addition to stationary drilling machines used in the metal machining industry, drilling devices, as mentioned above, have been used for some time as mobile equipment in the construction industry. Such drilling devices are used mainly with diamond-tipped drill bits. With such drill bits it is possible to produce holes of larger diameter and also to cut the holes through steel reinforced concrete structures.
A significant problem associated with the drill stand for such drilling devices is the guidance of the device. Due to the overhang or cantilever of the drilling device required for the largest hole diameter and because of the forces exerted especially when larger tools are employed, high overturning moments can develop on the guides and great bending and torsion stresses occur in the guide column. As indicated above, these drilling devices must be movable and, if possible, handled by one or at most two people. Therefore, the guide column cannot be made arbitrarily heavy, since it would increase the overall weight of the drilling assembly.
In known drilling assemblies, the guide column has been U-shaped or C-shaped in transverse section. The drilling device is mounted inside the guide column. Since the drilling device is positioned within the guide column, the machining of the guides is very costly and usually requires special tools. Further, because of the cross-sectional shape involved, only the part of the drilling device which supports the drill spindle can project outwardly from the guide column, with the result that the feeding mechanism for the drilling device must also be located inside the guide column. As a consequence, an involved design including gearing, a threaded spindle and a threaded nut are required.